Making sweet floppy drive music with a calculator

[Chris] says that he’s been pretty busy lately, leaving little opportunity for hacking. However he did manage to find a little time to put together a small project that has occupied his to-do list for a while – a floppy drive music controller.

We have seen hacks that use microcontrollers to actuate floppy drive motors before, but we can’t remember anything that used a calculator to do the job instead. While a microcontroller gives you plenty of I/O pins to play with, [Chris’] Ti-83+ only has two.

Even with the calculator’s I/O limitations, he didn’t find the task too overly difficult as he merely needed to hold a pair of the drive’s pins low, while pulsing two others. He modified a media player written for Ti calculators to output the necessary control signals, then he cranked out some tunes.

As you can see in the video below, his simple setup works quite well – not bad for just a few hours’ work.

Saying that floppy drives are monophonic is like saying that conventional loudspeakers are monophonic, or that PWM is monophonic: All of these things can be true, but that doesn’t mean that they must be.

Getting multiple, simultaneous frequencies out of the stepper on a floppy drive is a straight-forward thing. The results won’t be pretty, and there will be nothing practical about it, but just because it’s useless doesn’t mean it can’t (or shouldn’t) be done. :)

An excellent question. Notice that at the beginning, the Stop button in the media player centers the read/write head in the middle of the stepper track. Because of the limited clock cycles of the calculator, counting tracks to move the head back and forth across the 80 tracks of a typical 1.44MB 3.5″ drive is impractical without sound distortion. Therefore, the head-controlling routine is unrolled into a four-chunk loop, two of which move the head backwards for two wavelengths, two of which move the head forward for two wavelengths. This ensures that it stays more or less in the center of the track and gets around the inability to count tracks efficiently. If you look very closely, you can see a bit of vibration, but of course in general the frequency of the notes is faster than the framerate of my camera.